This project aims to systematically investigate relationships between structural anomalies in brains of persons who stutter (PWS) and functional properties of the speech motor system. The project's approach builds on recent important findings regarding white matter (WM) irregularities and other neuroanatomical anomalies in PWS by attempting to identify behavioral (kinematic and acoustic) correlates of these anomalies during speech and other auditory-motor tasks, and by providing mechanistic interpretations of these findings within an established computational modeling framework of the neural bases of speech. The project is comprised of two inter-related experimental investigations that utilize structural neuroimaging in combination with behavioral measures to investigate theoretically motivated hypotheses concerning possible neural deficits underlying stuttering. The neuroimaging involves the use of magnetic resonance imaging and diffusion tensor imaging in PWS and matched fluent controls to obtain subject-specific measures of a set of candidate neuroanatomical markers (quantitative measures of structural properties of white and gray matter) derived from prior findings. The first investigation studies correlations between the neuroanatomical markers and behavioral measures reflecting feedforward motor control: kinematic and reaction-time (RT) data collected from the subject groups while they perform carefully designed, simple RT and speech tasks. The second investigation studies correlations between the neuroanatomical markers and the use of auditory feedback in speech: data collected on the subjects'responses to real-time spectral and temporal perturbations in the auditory feedback of their own speech. Both investigations will also test for differences in the measures between the groups of PWS and controls, and will consider alternative hypotheses. Establishing relations between behavioral and neuroanatomical anomalies in stuttering should provide new insights into important structural substrates that could lead to or potentiate the expression of underlying neurofunctional deficits. Different combinations of neuro-structural and neuro-functional factors could be manifested in a range of influences on stuttering, from emotions to malfunctions of movement triggering and timing.